Given the need for greater mobility to support the tanks, in 1932 the Russians developed their first assault guns by utilising the T-26 chassis and mounting heavier weapons on them. Around 1935 they developed the AT-1 "Artilleriyskiy Tank" with the 76.2mm PS-3 gun mounted in an enclosed compartment. The design included a number of hatches for easy escape for the crew. Only 2 were ever produced. The 10 that were planned to be built in 1936 were cancelled in favour of the BT-7A tank.